Long-term fuel retention and release in JET ITER-Like Wall at ITER-relevant baking temperatures. (30th June 2017)

• Record Type: Journal Article
• Authors: Heinola, K.; Likonen, J.; Ahlgren, T.; Brezinsek, S.; De Temmerman, G.; Jepu, I.; Matthews, G.F.; Pitts, R.A.; Widdowson, A.
• Other Names: collab.
• Is Part Of: Nuclear fusion. Volume 57:Number 8(2017:Aug.)
• Publication Date: 2017-06-30
• Subjects: fuel retention -- ITER -- deposition -- divertor -- main chamber -- JET-ILW; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/aa747e
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: The fuel outgassing efficiency from plasma-facing components exposed in JET-ILW has been studied at ITER-relevant baking temperatures. Samples retrieved from the W divertor and Be main chamber were annealed at 350 and 240 °C, respectively. Annealing was performed with thermal desoprtion spectrometry (TDS) for 0, 5 and 15 h to study the deuterium removal effectiveness at the nominal baking temperatures. The remained fraction was determined by emptying the samples fully of deuterium by heating W and Be samples up to 1000 and 775 °C, respectively. Results showed the deposits in the divertor having an increasing effect to the remaining retention at temperatures above baking. Highest remaining fractions 54 and 87 % were observed with deposit thicknesses of 10 and 40 μ m, respectively. Substantially high fractions were obtained in the main chamber samples from the deposit-free erosion zone of the limiter midplane, in which the dominant fuel retention mechanism is via implantation: 15 h annealing resulted in retained deuterium higher than 90 % . TDS results from the divertor were simulated with TMAP7 calculations. The spectra were modelled with three deuterium activation energies resulting in good agreement with the experiments.